Socio-technical determinants of perceived disgust, health risk, and acceptance of decentralised wastewater treatment and reuse: An experimental study in Bengaluru, India.

Decentralised wastewater treatment and reuse offers substantial potential to alleviate urban freshwater scarcity, yet its successful implementation depends on public acceptance and positive perceptions. While prior research suggests that the quality of the treated water and the physical contact during reuse influence perceived disgust, health risk, and acceptance, experimental evidence on how different system configurations shape these outcomes remains limited. We conducted a randomised online experiment (N = 702) with residents of Bengaluru, India, where decentralised wastewater treatment and reuse is mandatory for buildings of a certain size. Participants received detailed information about one out of 15 configurations that differed in treatment quality and level of physical contact during reuse, including accompanying information on financial, environmental, and water safety and security implications for users. Subsequently, perceived disgust, health risk, and acceptance was assessed. The results of linear regression analyses show that higher treatment quality significantly reduced perceived disgust and health risk. No such effects were found for different levels of physical contact during reuse, indicating openness even to higher-contact reuse. Acceptance was associated with lower perceived health risk but was not explained by treatment quality or contact level. This may reflect trade-offs in acceptance evaluations: higher treatment quality raises financial costs, whereas higher-contact reuse provides greater environmental and water security benefits through increased recycling. These insights provide guidance for the design and governance of decentralised wastewater systems in water-scarce urban contexts.